Experimental and numerical study of a barge-type FOWT platform under wind and wave load

Abstract

In this study, a floating barge moon pool platform model equipped with an NREL 5 MW wind turbine and mooring systems was numerically and experimentally tested under wave and wind loads to analyze the hydrodynamic performance and stability of the barge platform and the mooring system in a 50 m water depth condition. The numerical model was based on ANSYS AQWA, and this hydrodynamic model included nonlinear hydrostatic and Froude–Krylov forces, diffraction/radiation forces obtained from the linear potential theory, and Morison forces to consider viscous effects on the heave plates. The experiment model was a 1:64 scaled barge platform with an NREL 5 MW wind turbine scaled in the same ratio. Both full coupling platform were simulated under three conditions, namely free decay test, regular wave test, and irregular wave test, including a typhoon extreme case, with wind operation and parking.First, the hydrodynamic model was calibrated against the free decay test results. Consequently, a good agreement was achieved by calibrating the mooring properties of the experiment model. A comparison of the regular wave cases was then performed, with the same trend of results observed for the surge, heave, and pitch motions of the floating barge system. Finally, irregular model tests, which aimed to measure the dynamics of the barge platform and the mooring system in a 50-year sea state in Taiwan offshore, were conducted. The motion responses of the barge platform and the mooring tensions were recorded and compared with full coupled dynamic analysis results. The DNV GL standards were used to check the reliability of the mooring system and the stability of the barge platform.